Luni-tidal tellurian.



l Patented May I4, |901. T. MGDUNOUGH.

LUNl-TIDAL 'TELLURIAIL (Application ma oct. 16.1900.)

(Nq Model.) 2 Sheets-Sheet l.

UNITED STATES Y PATENT OFFICE.

. THOMAS MCDONOUGH, OF OTTAWA, ILLINOIS.

LUNI-TIDAL TELLURIAN.

SPECIFICATION forming part of Letters Patent No. 674,277, dated May 14,1901.

Application led October 16, 1900. Serial No. 33,241. (No model.)

To all whom it may concern:

Be it known that I, THOMAS MODONOUGH, of Ottawa, in the county ofLasalle and State of Illinois, have invented a new and usefnlImprovementin Luni-Tidal Tellurians, of which the following is a specification.

My invention is an improved apparatus in the nature of a telluriandesigned to illustrate to p upils in a simple and convincing way thecause of tides and the phases of the moon and which may be also utilizedorillustrating the causes of eclipses.

It consists in the construction and arrangement of the device which Iwill now proceed to describe, reference being had to the accompanyingdrawings, in which- Figure l is a face view of the instrument, showingthe position of parts for new moon and showing in dotted lines theseveral phases of the moon. Fig. 2 is a sectional view of the same.Figs. 3 and 4 are small views illustrating the use for explainingeclipses.

In the drawings, A represents a base-board, which for convenience oftransportation may be a simple flat board, preferably painted'l black,but for which the blackboard ot' the school-room may be substituted whenit is not desired to move the apparatus about. In the center of theboard is xedly placed a standard B, to which is rigidly attached abevel-wheel b. To the top of the standard B is detachably fastened by ascrew a a pendent hemispherical shell O, which descends to the plane ofthe base-board and represents the earth.

On the standard B above the bevel-wheel h there is loosely hung an armD, which extends out through a slot in the shell C and supports aradially-projecting shaft E, bearing on its outer end a globe M,representing the moon. The inner end of the arm D is bent to form arectangular frame d, through the upper and lower ends of which thestandard B freely passes and one side of which forms a bearing for theinner end of the radial shaft E. On the inner end of this radial shaftis rigidly keyed a bevel-wheel h', which rides upon the fixedbevel-wheel b, and as the radial shaft E is swung around the shell C,representing the earth, the shaft E is made to rotate about its axis forthe purpose hereinafter described.

At a suitable point on the board near the circumference described by themoon-globe M and approximately in the moons orbit there is mounted abrightly-polished plateS, representing the sun. representing the earth,there is arranged an arm F, which at one end is secured to the top ofarm D and in its middle is screwed to the top of the standard B, outsideof the shell C, and extends upon the opposite side a considerabledistance and terminates in an eye f. To this eye and tothe outer end ofthe' arm D there is attached an elliptical ring e. A similar ellipticalring c' is attached to the board and incloses the earth, the major axisof said ring being on a line passing from the sun S to the earth C.

On the outer end of the shaft E is theglobe C, which represents themoon, and which has one half of its surface painted black and the otherhalf, which is next tothe sun gilded or painted white. As the armbearing the moon-globe and its shaft revolves, the gear-wheel b,traveling around on the stationary wheel b,causes the moon-globe to make4one complete rotation about its shaft for each complete revolutionaround the earth, and this causes the bright side of the moon to bealways held toward the sun through all the phases 0f the rnoon. Viewingthe apparatus from acentral posi tion above the earth in line withthecenter of revolution of the moon,it will be seen that j ust after themoon has passed the sun, as shown in full lines, a little crescent ofthe gilded face of the moon only will be visible from the earth, and wehave what is called the new moon. At a point No. l, representingonequarter of a revolution, we have the first quarter of the moon, inwhich one-half its surface is visible from the earth. At the positionNo.

2 we have the full moon on the opposite sidev of the earth from the sunand with all the moons face visible from the earth. At No. 3 we have thelast quarter, showing one-half its surface on the wane, and when themoon reaches a position in line with and between the sun and earth thefull dark side of the moon will be presented to the earth and no moonwill lbe visible.

In explaining the value of the oval rings e and e I would state that itis well known that the tides are caused by the attractive influssA Ontop of the shell C, v

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earth by the sun and moon.

ence exerted upon the mobile waters of the This influence causes thewaters of the earth to be heaped up on the side of the earth next to thesun and moon and also on the diametrically opposite side and to bedepressed at intermediate;

points. This attractive influence of the moon on the water isillustrated by the oval e and of the sun by the oval e, the ovalsrepresenting at the prolate ends of the ellipse the high tide and at theoblate or flatten ed sides the low tide. When the moon is in line withthe sun and earth, as shown either atf ull moon or when the moon has itsdark side to the earth,the attractive in luences of the sun and moon onthe water act in unison. This is shown by the two el lipses e and e',which have their prolate ends together, and the result is the springtides when the rise and fall is at its maximum. 'When the moon is,however, at its first and last quarter, the major axes of the twoellipses are at right angles, andv as the influence of the sun isconnteracted bytheinluence ofthe moon there is a minimum tide which isknown as the neap tide, which only represent-s the difference betweenthe attraction of the sun and moon. Instead ofthe oval rings e and e',cords, wires, or other devices may be employed to illustrate theprinciple in the same way.

To utilize my invention so as to employ it for illustrating the eclipsesof sun or moon, the position ot the sun should be removed a littlefarther from the earth. Then when the moon comes between the sun and theearth we have the eclipse of the sun, as seen in Fig. 3, and when theearth comes between the sun and moon we have an eclipse of the moon, asseen in Fig. i. By means of my apparatus these usually-nnintelligiblephenomena are made perfectly clear and in a way so simple as to beunderstood even by a child.

Having thus described my invention,what I claim as new, and desire tosecure by Letters Patent, is-

1. A tellurian comprising a basic support, a standard mounted thereonand bearing a hemispherical representation of the earth and a gear-wheelwithin it, a swinging arm mounted upon the standard, a rotating shaftsustained by said swinging arm and bearing on its outer end a globerepresenting the moon, one half of which is made dark and the otherlight, and having on its inner end a gearwheel in mesh with andtraversing lthe stationary gear-wheel, and a representation of the sunfixed to the basic support at a point approximately within the swing ororbit of the moon substantially as and for the `purpose described. i

2. Atellurian comprising a representation of the earth, a representationof the sun remote from the earth, a representation of the moon,supporting devices for the same and means for swinging it about theearth, and two oval rings or oblong markings, the one attached to themoon-moving devices and surrounding the earth, and the other surroundingthe earth in relation fixed with reference to the sun substantially asand for the purpose described. V

3. The combination with the hemispherical shell C representing theearth; of a supporting-standard within Athe same, a swinging armcarrying on its end a representation of the moon, another arm projectingbeyond the earth in the opposite direction from the moon and carrying anoblong ring or marking surrounding the earth and representing thelumi-tidal influence thereupon substantially as described.

4E. The combination with a base-board; of

' a standard bearing a rigid gear-wheel, an arm bent at its inner end toform a rectangle and having a bearing in its upper and lower ends forthe standard, a rotating shaft arranged radially and supported inbearings in the outer end of the radial arm and also in the side of therectangulaifraxne at the inner end of the arm, and having a rigidgear-wheel on its inner end and a globe on the outer end, ahemispherical shell inclosing said gears and representing the earth, anda second arm secured to the top of the first-named arm and to thestandard by a screw which also clamps and secures the hemisphericalshell, substantially as shown and described.

5. A tellurian having a moon-revolving gear, a central representationot' the earth, and an oval or oblong device representing the lunar tideconnected to the moon-revolving gear and surrounding the earthsubstantially as shown and described.

`A tellurian having a central representation of the earth, a removedrepresentation of the sun, and an oval demarcation around the earthhaving its longitudinal axis in line with the sun substantially asdescribed.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

THOMAS MCDONOUGII.

Witnesses:

J. L. FERGUSON, CLEMENT CURTIS.

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